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Monday, June 20, 2011

Ancient Male Hominids Stayed At Home While Females Wandered

According to a study of hominids — the early ancestors of humans — it appears that women were likely to leave their natal groups while men spent their lives in the nearby surroundings of their birthplace.

Those were the results from researchers looking at the enamel of fossilised teeth millions of years old. A similar female migration pattern was found in chimpanzees and bonobos but not in gorillas and many other primates. The findings increase our knowledge of how our ancestors lived some two million years ago, according to the scientists (doi:10.1038/nature10149).

Sandi Copeland of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany and her team examined 19 fossilized teeth found in caves in South Africa. Eleven of the teeth belonged to members of the Paranthropus robustus and the other eight to Australopithecus africanus ancestors.

Both hominids are related to Australopithecus from which humans evolved into the Homo genus and eventually modern man. The teeth are between 2.4 and 1.7 million years old.

The researchers used strontium isotope analysis of the teeth enamel. Strontium is a metal found in stones and soil. Different types of stone and geological regions are defined by different strontium signatures. The strontium is taken up by plants and animals and then consumed by the hominids. It is then stored in trace amounts in their teeth up until about the age of eight.

Copeland’s team determined that most of the larger teeth - probably from males - show strontium isotopes from the vicinity where the fossils were recovered. And most of the smaller teeth - likely to be from females - revealed strontium isotopes indicating that they grew up away from the caves where they were later found.

The minimum distance from the next region with a different signature is between two and three kilometres to the south-east and five to six kilometres to the north-west, according to the research team.

This would lead one to believe that the females must have travelled at least that distance to join a different group and mate with a male partner. The men may have remained in their home region because they preferred the caves that they knew and the food available there.

Monday, June 20, 2011

Ancient Male Hominids Stayed At Home While Females Wandered

According to a study of hominids — the early ancestors of humans — it appears that women were likely to leave their natal groups while men spent their lives in the nearby surroundings of their birthplace.

Those were the results from researchers looking at the enamel of fossilised teeth millions of years old. A similar female migration pattern was found in chimpanzees and bonobos but not in gorillas and many other primates. The findings increase our knowledge of how our ancestors lived some two million years ago, according to the scientists (doi:10.1038/nature10149).

Sandi Copeland of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany and her team examined 19 fossilized teeth found in caves in South Africa. Eleven of the teeth belonged to members of the Paranthropus robustus and the other eight to Australopithecus africanus ancestors.

Both hominids are related to Australopithecus from which humans evolved into the Homo genus and eventually modern man. The teeth are between 2.4 and 1.7 million years old.

The researchers used strontium isotope analysis of the teeth enamel. Strontium is a metal found in stones and soil. Different types of stone and geological regions are defined by different strontium signatures. The strontium is taken up by plants and animals and then consumed by the hominids. It is then stored in trace amounts in their teeth up until about the age of eight.

Copeland’s team determined that most of the larger teeth - probably from males - show strontium isotopes from the vicinity where the fossils were recovered. And most of the smaller teeth - likely to be from females - revealed strontium isotopes indicating that they grew up away from the caves where they were later found.

The minimum distance from the next region with a different signature is between two and three kilometres to the south-east and five to six kilometres to the north-west, according to the research team.

This would lead one to believe that the females must have travelled at least that distance to join a different group and mate with a male partner. The men may have remained in their home region because they preferred the caves that they knew and the food available there.